Mobile terminal

ABSTRACT

The disclosure provides a mobile terminal including: a body including a first frame and a second frame configured to slide in a first direction with respect to the first frame and slide in a second direction; a flexible display configured to cover a part of the body, wherein a front surface area of the flexible display is configured to vary according to the sliding of the second frame; and a rolling hinge disposed on a rear surface of the flexible display and deformable in response to bending deformation of the flexible display. The rolling hinge includes: a first rolling sheet including a first hinge hole; a second rolling sheet overlapping with the first rolling sheet, wherein the second rolling sheet includes a second hinge hole overlapping at least partially with the first hinge hole; and a first rivet configured to penetrate the first hinge hole and the second hinge hole.

CROSS-REFERENCE TO RELATED APPLICATION(S)

Pursuant to 35 U.S.C. § 119 (a), this application claims the benefit ofan earlier filing date and right of priority to InternationalApplication No. PCT/KR2020/012361 filed on Sep. 14, 2020, the contentsof which are hereby incorporated by reference herein in its entirety.

BACKGROUND Field

The present disclosure relates to a mobile terminal, and moreparticularly, to a mobile terminal that has a flexible display and iscapable of extending a size of a screen while the display is scrolledand slid at the same time.

Discussion of the Related Art

Terminals may be generally classified as mobile/portable terminals orstationary terminals according to their mobility. Mobile terminals mayalso be classified as handheld terminals or vehicle mounted terminalsaccording to whether or not a user can directly carry the terminal.

In recent years, because of a development of a broadcasting technologyand a network technology, functions of the display device have also beenconsiderably diversified, and a performance of the device has beenimproved accordingly. That is, the display device has been developed toprovide not only broadcast contents but also various other contents tothe user. For example, the display device may provide game play, musiclistening, internet shopping, user customized information, and the likeusing various applications as well as programs received from thebroadcasting station. In order to perform such extended functions, thedisplay device may be basically connected to other devices or networksusing various communication protocols, and may provide the user with aubiquitous computing environment. In other words, the display device hasevolved into a smart device that enables connectivity to a network andcontinuous computing.

Recently, a flexible display having sufficient elasticity and capable oflarge deformation has been developed. The size of a mobile terminal canbe varied using the deformable nature of the flexible display. For themobile terminal having such a variable structure, changing the size ofthe mobile terminal should be stably performed, and there is a need fora structure to support the extended display unit to maintain a flatstate of the display unit.

SUMMARY

Accordingly, the present disclosure is directed to a mobile terminalthat substantially obviates one or more problems due to limitations anddisadvantages of the related art.

An object of the present disclosure is to provide a mobile terminal forimproving the durability of a flexible display by preventing a point atwhich the flexible display is bent from being limited to a specificposition.

Another object of the present disclosure is to solve a problem that asupport bar in a rolling hinge is transferred to a flexible display anddisplayed on the front surface of the flexible display due to stress inthe back-side structure of the flexible display.

Additional advantages, objects, and features of the disclosure will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of thedisclosure. The objectives and other advantages of the disclosure may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the disclosure, as embodied and broadly described herein, amobile terminal may include: a body including a first frame and a secondframe configured to slide in a first direction with respect to the firstframe and slide in a second direction opposite to the first direction; aflexible display configured to cover a part of the body, wherein a frontsurface area of the flexible display is configured to vary according tothe sliding of the second frame; and a rolling hinge disposed on a rearsurface of the flexible display and deformable in response to bendingdeformation of the flexible display. The rolling hinge may include: afirst rolling sheet including a first hinge hole; a second rolling sheetoverlapping with the first rolling sheet, wherein the second rollingsheet includes a second hinge hole overlapping at least partially withthe first hinge hole; and a first rivet configured to penetrate thefirst hinge hole and the second hinge hole.

The first rivet may be smaller than the first and second hinge holes inthe first direction.

The first rivet may include wings at ends, each of which may be greaterthan the first and second hinge holes in the first direction.

A plurality of first hinge holes may be arranged and spaced apart fromeach other in the first direction and in a third direction perpendicularto the first direction, and a plurality of second hinge holes may bearranged and spaced apart from each other in the first direction and inthe third direction.

The first and second hinge holes may be elongated in the thirddirection.

First hinge holes adjacent in the first direction may be arrangedalternately in the third direction, and second hinge holes adjacent inthe first direction may be arranged alternately in the third direction.

The second rolling sheet may further include a third hinge hole. Therolling hinge may further include: a third rolling sheet overlappingwith the second rolling sheet, wherein the third rolling sheet includesa fourth hinge hole overlapping at least partially with the third hingehole; and a second rivet configured to penetrate the third hinge holeand the fourth hinge hole.

A plurality of third hinge holes may be arranged and spaced apart fromeach other in the first direction and in a third direction perpendicularto the first direction, and a plurality of fourth hinge holes may bearranged and spaced apart from each other in the first direction and inthe third direction.

The rolling hinge may include a plurality of support bars attached tothe first rolling sheet and arranged side by side along the firstdirection, and wherein each of the plurality of support bars is extendedin a third direction perpendicular to the first direction.

The flexible display may include: a fixed portion fixed to the body; anda variable portion capable of bending deformation, wherein the variableportion is not fixed to the body. The rolling hinge may be disposed on arear surface of the variable portion.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

As is apparent from the above description, the present disclosure haseffects as follows.

The mobile terminal according to the present disclosure may adjust thesize of a screen according to the need, thereby satisfying bothportability and utility.

The mobile terminal according to the present disclosure may prevent thedisplay from being damaged since stress is not concentrated at aspecific point of the display.

According to the present disclosure, the rivet configured to penetratehinge holes is used for coupling between a plurality of rolling sheetsinstead of an adhesive, thereby preventing stress from increasing due tothe repulsive force of the adhesive.

According to the present disclosure, the compression of the adhesive,which occurs at the coupling point of the support bar, may be resolved,thereby providing the screen with no waviness and preventing the supportbar from being transferred to the variable portion.

Further scope of applicability of the present disclosure will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the disclosure, aregiven by illustration only, since various changes and modificationswithin the spirit and scope of the disclosure will become apparent tothose skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description given herein below and the accompanying drawings,which are given by illustration only, and thus are not limitative of thepresent disclosure, and wherein:

FIG. 1 is a block diagram of a mobile terminal in accordance with thepresent disclosure;

FIG. 2 is a front view of a first state and a second state of the mobileterminal in accordance with an embodiment;

FIG. 3 is a rear view of the first state and the second state of themobile terminal in accordance with an embodiment;

FIGS. 4 and 5 are exploded perspective views of the mobile terminal inaccordance with an embodiment;

FIG. 6 is a side view of the mobile terminal as viewed from a thirddirection;

FIG. 7 is a view showing a driving unit of the mobile terminal inaccordance with an embodiment;

FIG. 8 is a cross-sectional view taken along lines A-A and B-B in FIG.2;

FIG. 9 is a view illustrating a display unit and a rolling plate of themobile terminal in accordance with an embodiment;

FIG. 10 is a view illustrating an issue raised in an extendable mobileterminal;

FIG. 11 is a cross-sectional view taken along lines C-C and D-D in FIG.2;

FIG. 12 is a cross-sectional view taken along lines E-E and F-F in FIG.11;

FIG. 13 is a view showing an expanded side portion and a guide hook ofthe mobile terminal in accordance with an embodiment;

FIG. 14 is a view showing a slide frame and a second frame of the mobileterminal;

FIG. 15 is a graph showing phase distortion in the mobile terminal;

FIG. 16 is a conceptual view for explaining causes of the phasedistortion of FIG. 15;

FIG. 17 is a view for explaining a slip phenomenon occurring whencurvature changes in a structure consisting of a plurality of layers;

FIG. 18 is a view for explaining an embodiment of coupling a pluralityof layers with an adhesive;

FIG. 19 is a view showing an embodiment of the plurality of layers ofthe mobile terminal;

FIG. 20 is a cross-sectional view taken along line G-G of FIG. 19according to one embodiment;

FIG. 21 is an exploded perspective view of FIG. 19; and

FIG. 22 is a cross-sectional view taken along line G-G of FIG. 19according to another embodiment.

DETAILED DESCRIPTION OF THE DISCLOSURE

Description will now be given in detail according to exemplaryembodiments disclosed herein, with reference to the accompanyingdrawings. For the sake of brief description with reference to thedrawings, the same or equivalent components may be provided with thesame reference numbers, and description thereof will not be repeated. Ingeneral, a suffix such as “module” and “unit” may be used to refer toelements or components. Use of such a suffix herein is merely intendedto facilitate description of the specification, and the suffix itself isnot intended to give any special meaning or function. In the presentdisclosure, that which is well-known to one of ordinary skill in therelevant art has generally been omitted for the sake of brevity. Theaccompanying drawings are used to help easily understand varioustechnical features and it should be understood that the embodimentspresented herein are not limited by the accompanying drawings. As such,the present disclosure should be construed to extend to any alterations,equivalents and substitutes in addition to those which are particularlyset out in the accompanying drawings.

It will be understood that although the terms first, second, etc. may beused herein to describe various elements, these elements should not belimited by these terms. These terms are generally only used todistinguish one element from another.

It will be understood that when an element is referred to as being“connected with” another element, the element can be directly connectedwith the other element or intervening elements may also be present. Incontrast, when an element is referred to as being “directly connectedwith” another element, there are no intervening elements present.

A singular representation may include a plural representation unless itrepresents a definitely different meaning from the context.

Terms such as “include” or “has” are used herein and should beunderstood that they are intended to indicate an existence of severalcomponents, functions or steps, disclosed in the specification, and itis also understood that greater or fewer components, functions, or stepsmay likewise be utilized.

FIG. 1 is a block diagram of a mobile terminal in accordance with thepresent disclosure.

The mobile terminal 100 is shown having components such as a wirelesscommunication unit 110, an input unit 120, a sensing unit 140, an outputunit 150, an interface unit 160, a memory 170, a controller 180, and apower supply unit 190. Referring now to FIG. 1, the mobile terminal 100is shown having wireless communication unit 110 configured with severalcommonly implemented components. It is understood that implementing allof the illustrated components is not a requirement, and that greater orfewer components may alternatively be implemented.

More specifically, the wireless communication unit 110 typicallyincludes one or more modules which permit communications such aswireless communications between the mobile terminal 100 and a wirelesscommunication system, communications between the mobile terminal 100 andanother mobile terminal, communications between the mobile terminal 100and an external server. Further, the wireless communication unit 110typically includes one or more modules which connect the mobile terminal100 to one or more networks.

To facilitate such communications, the wireless communication unit 110includes one or more of a broadcast receiving module 111, a mobilecommunication module 112, a wireless Internet module 113, a short-rangecommunication module 114, and a location information module 115.

Regarding the wireless communication unit 110, the broadcast receivingmodule 111 is typically configured to receive a broadcast signal and/orbroadcast associated information from an external broadcast managingentity via a broadcast channel. The broadcast channel may include asatellite channel, a terrestrial channel, or both. In some embodiments,two or more broadcast receiving modules 111 may be utilized tofacilitate simultaneously receiving of two or more broadcast channels,or to support switching among broadcast channels.

The mobile communication module 112 can transmit and/or receive wirelesssignals to and from one or more network entities. Typical examples of anetwork entity include a base station, an external mobile terminal, aserver, and the like. Such network entities form part of a mobilecommunication network, which is constructed according to technicalstandards or communication methods for mobile communications (forexample, Global System for Mobile Communication (GSM), Code DivisionMulti Access (CDMA), CDMA2000 (Code Division Multi Access 2000), EV-DO(Enhanced Voice-Data Optimized or Enhanced Voice-Data Only), WidebandCDMA (WCDMA), High Speed Downlink Packet access (HSDPA), HSUPA (HighSpeed Uplink Packet Access), Long Term Evolution (LTE), LTE-A (Long TermEvolution-Advanced), and the like).

Examples of wireless signals transmitted and/or received via the mobilecommunication module 112 include audio call signals, video (telephony)call signals, or various formats of data to support communication oftext and multimedia messages.

The wireless Internet module 113 is configured to facilitate wirelessInternet access. This module may be internally or externally coupled tothe mobile terminal 100. The wireless Internet module 113 may transmitand/or receive wireless signals via communication networks according towireless Internet technologies.

Examples of such wireless Internet access include Wireless LAN (WLAN),Wireless Fidelity (Wi-Fi), Wi-Fi Direct, Digital Living Network Alliance(DLNA), Wireless Broadband (WiBro), Worldwide Interoperability forMicrowave Access (WiMAX), High Speed Downlink Packet Access (HSDPA),HSUPA (High Speed Uplink Packet Access), Long Term Evolution (LTE),LTE-A (Long Term Evolution-Advanced), and the like. The wirelessInternet module 113 may transmit/receive data according to one or moreof such wireless Internet technologies, and other Internet technologiesas well.

In some embodiments, when the wireless Internet access is implementedaccording to, for example, WiBro, HSDPA, HSUPA, GSM, CDMA, WCDMA, LTE,LTE-A and the like, as part of a mobile communication network, thewireless Internet module 113 performs such wireless Internet access. Assuch, the Internet module 113 may cooperate with, or function as, themobile communication module 112.

The short-range communication module 114 is configured to facilitateshort-range communications. Suitable technologies for implementing suchshort-range communications include BLUETOOTH™, Radio FrequencyIDentification (RFID), Infrared Data Association (IrDA), Ultra-WideBand(UWB), ZigBee, Near Field Communication (NFC), Wireless-Fidelity(Wi-Fi), Wi-Fi Direct, Wireless USB (Wireless Universal Serial Bus), andthe like. The short-range communication module 114 in general supportswireless communications between the mobile terminal 100 and a wirelesscommunication system, communications between the mobile terminal 100 andanother mobile terminal 100, or communications between the mobileterminal and a network where another mobile terminal 100 (or an externalserver) is located, via wireless area networks. One example of thewireless area networks is a wireless personal area networks.

The location information module 115 is generally configured to detect,calculate, derive or otherwise identify a position of the mobileterminal. As an example, the location information module 115 includes aGlobal Position System (GPS) module, a Wi-Fi module, or both. Ifdesired, the location information module 115 may alternatively oradditionally function with any of the other modules of the wirelesscommunication unit 110 to obtain data related to the position of themobile terminal. As one example, when the mobile terminal uses a GPSmodule, a position of the mobile terminal may be acquired using a signalsent from a GPS satellite. As another example, when the mobile terminaluses the Wi-Fi module, a position of the mobile terminal can be acquiredbased on information related to a wireless access point (AP) whichtransmits or receives a wireless signal to or from the Wi-Fi module.

The input unit 120 includes a camera 121 for obtaining images or video,a microphone 122, which is one type of audio input device for inputtingan audio signal, and a user input unit 123 (for example, a touch key, apush key, a mechanical key, a soft key, and the like) for allowing auser to input information. Data (for example, audio, video, image, andthe like) is obtained by the input unit 120 and may be analyzed andprocessed by controller 180 according to device parameters, usercommands, and combinations thereof.

Such cameras 121 may process image frames of still pictures or videoobtained by image sensors in a video or image capture mode. Theprocessed image frames can be displayed on the display unit 151 orstored in memory 170. In some cases, the cameras 121 may be arranged ina matrix configuration to permit a plurality of images having variousangles or focal points to be input to the mobile terminal 100. Asanother example, the cameras 121 may be located in a stereoscopicarrangement to acquire left and right images for implementing astereoscopic image.

The microphone 122 is generally implemented to permit audio input to themobile terminal 100. The audio input can be processed in various mannersaccording to a function being executed in the mobile terminal 100. Ifdesired, the microphone 122 may include assorted noise removingalgorithms to remove unwanted noise generated in the course of receivingthe external audio.

The user input unit 123 is a component that permits input by a user.Such user input may enable the controller 180 to control operation ofthe mobile terminal 100. The user input unit 123 may include one or moreof a mechanical input element (for example, a key, a button located on afront and/or rear surface or a side surface of the mobile terminal 100,a dome switch, a jog wheel, a jog switch, and the like), or atouch-sensitive input, among others. As one example, the touch-sensitiveinput may be a virtual key or a soft key, which is displayed on a touchscreen through software processing, or a touch key which is located onthe mobile terminal at a location that is other than the touch screen.On the other hand, the virtual key or the visual key may be displayed onthe touch screen in various shapes, for example, graphic, text, icon,video, or a combination thereof.

The sensing unit 140 is typically implemented using one or more sensorsconfigured to sense internal information of the mobile terminal, thesurrounding environment of the mobile terminal, user information, andthe like. For example, the sensing unit 140 may alternatively oradditionally include other types of sensors or devices, such as aproximity sensor 141 and an illumination sensor 142, a touch sensor, anacceleration sensor, a magnetic sensor, a G-sensor, a gyroscope sensor,a motion sensor, an RGB sensor, an infrared (IR) sensor, a finger scansensor, a ultrasonic sensor, an optical sensor (for example, camera121), a microphone 122, a battery gauge, an environment sensor (forexample, a barometer, a hygrometer, a thermometer, a radiation detectionsensor, a thermal sensor, and a gas sensor, among others), and achemical sensor (for example, an electronic nose, a health care sensor,a biometric sensor, and the like), to name a few. The mobile terminal100 may be configured to utilize information obtained from sensing unit140, and in particular, information obtained from one or more sensors ofthe sensing unit 140, and combinations thereof.

The output unit 150 is typically configured to output various types ofinformation, such as audio, video, tactile output, and the like. Theoutput unit 150 is shown having a display unit 151, an audio outputmodule 152, a haptic module 153, and an optical output module 154. Thedisplay unit 151 may have an inter-layered structure or an integratedstructure with a touch sensor in order to facilitate a touch screen. Thetouch screen may provide an output interface between the mobile terminal100 and a user, as well as function as the user input unit 123 whichprovides an input interface between the mobile terminal 100 and theuser.

The audio output module 152 is generally configured to output audiodata. Such audio data may be obtained from any of a number of differentsources, such that the audio data may be received from the wirelesscommunication unit 110 or may have been stored in the memory 170. Theaudio data may be output during modes such as a signal reception mode, acall mode, a record mode, a voice recognition mode, a broadcastreception mode, and the like. The audio output module 152 can provideaudible output related to a particular function (e.g., a call signalreception sound, a message reception sound, etc.) performed by themobile terminal 100. The audio output module 152 may also be implementedas a receiver, a speaker, a buzzer, or the like.

A haptic module 153 can be configured to generate various tactileeffects that a user feels, perceive, or otherwise experience. A typicalexample of a tactile effect generated by the haptic module 153 isvibration. The strength, pattern and the like of the vibration generatedby the haptic module 153 can be controlled by user selection or settingby the controller. For example, the haptic module 153 may outputdifferent vibrations in a combining manner or a sequential manner.

An optical output module 154 can output a signal for indicating an eventgeneration using light of a light source. Examples of events generatedin the mobile terminal 100 may include message reception, call signalreception, a missed call, an alarm, a schedule notice, an emailreception, information reception through an application, and the like.

The interface unit 160 serves as an interface with various types ofexternal devices that can be coupled to the mobile terminal 100. Theinterface unit 160, for example, may include any of wired or wirelessports, external power supply ports, wired or wireless data ports, memorycard ports, ports for connecting a device having an identificationmodule, audio input/output (I/O) ports, video I/O ports, earphone ports,and the like. In some cases, the mobile terminal 100 may performassorted control functions associated with a connected external device,in response to the external device being connected to the interface unit160.

The memory 170 is typically implemented to store data to support variousfunctions or features of the mobile terminal 100. For instance, thememory 170 may be configured to store application programs executed inthe mobile terminal 100, data or instructions for operations of themobile terminal 100, and the like. Some of these application programsmay be downloaded from an external server via wireless communication.Other application programs may be installed within the mobile terminal100 at time of manufacturing or shipping, which is typically the casefor basic functions of the mobile terminal 100 (for example, receiving acall, placing a call, receiving a message, sending a message, and thelike). It is common for application programs to be stored in the memory170, installed in the mobile terminal 100, and executed by thecontroller 180 to perform an operation (or function) for the mobileterminal 100.

The controller 180 typically functions to control overall operation ofthe mobile terminal 100, in addition to the operations associated withthe application programs. The controller 180 may provide or processinformation or functions appropriate for a user by processing signals,data, information and the like, which are input or output, or activatingapplication programs stored in the memory 170.

To drive the application programs stored in the memory 170, thecontroller 180 may be implemented to control a predetermined number ofthe components mentioned above with reference to FIG. 1. Moreover, thecontroller 180 may be implemented to combinedly operate two or more ofthe components provided in the mobile terminal 100 to drive theapplication programs.

The power supply unit 190 can be configured to receive external power orprovide internal power in order to supply appropriate power required foroperating elements and components included in the mobile terminal 100.The power supply unit 190 may include a battery, and the battery may beconfigured to be embedded in the terminal body, or configured to bedetachable from the terminal body.

Some or more of the components may be operated cooperatively to embodyan operation, control or a control method of the mobile terminal inaccordance with embodiments of the present disclosure. Also, theoperation, control or control method of the mobile terminal may berealized on the mobile terminal by driving of one or more applicationproblems stored in the memory 170.

FIG. 2 is a front view of a first state and a second state of the mobileterminal in accordance with an embodiment, and FIG. 3 is a rear view ofthe first state and the second state of the mobile terminal inaccordance with an embodiment. FIGS. 2(a) and 3(a) are views showing thefirst state in which the mobile terminal is contracted, and FIGS. 2(b)and 3(b) are views showing the second state in which the mobile terminalis extended.

As shown in the figures, the mobile terminal 100 in the first state isin a contracted position, and has a smaller size than the mobileterminal 100 in the second state. In addition, the size of the displayunit 151 positioned on the front of the mobile terminal 100 is alsosmaller than in the second state. The mobile terminal 100 in the firststate may be extended in a first direction D1 to switch to the secondstate. In the second state, as shown in FIG. 2(b), the size of themobile terminal 100 and the size of the display unit 151 positioned onthe front of the mobile terminal 100 are larger than in the first state,while the size of the display unit 151 positioned on the rear of themobile terminal 100 is reduced as shown in FIG. 3(b). That is, a part ofthe display units 151 positioned on the rear of the mobile terminal 151in the first state moves to the front of the mobile terminal 100 in thesecond state.

In the following description, the direction in which the mobile terminal100 and the display unit 151 thereof are extended or enlarged is definedas a first direction D1, and the direction in which the mobile terminalcontracts or retracts or is reduced to switch from the second state tothe first state is defined as a second direction D2. A directionperpendicular to the first and second directions D1 and D2 is defined asa third and fourth directions. Description will be made on theassumption that the first and second directions are horizontaldirections and the third and fourth directions are vertical directions.However, depending on the arrangement of the mobile terminal 100, thefirst and second directions may be vertical directions and the thirddirection may be a horizontal direction.

As such, a flexible display unit 151 which is bendable may be used asthe display unit such that the position of the display unit may bevaried. The flexible display unit 151 may be a display unit capable ofmaintaining a flat state like a conventional flat panel display andcapable of warping, bending, folding, twisting, or rolling like paper.The flexible display unit 151 refers to a display which is manufacturedon a thin and flexible substrate and is thus lightweight and robust asnot to be easily broken. The flexible display unit according the presentdisclosure may be bent in a specific direction, and may be arranged suchthat the curvature thereof may change in the first direction.

In addition, an electronic paper is a display technology to whichproperties of general ink are applied. The electronic paper may bedifferent from the conventional flat panel display in using reflectedlight. The electronic paper may change information using a twisted ballor electrophoresis using a capsule.

In a state in which the flexible display unit 151 is not deformed (e.g.,a state of having an infinite curvature radius, hereinafter referred toas a basic state), a display region of the flexible display unit 151becomes flat. In a state in which the flexible display unit 151 isdeformed by an external force from the basic state (e.g., a state ofhaving a finite radius of curvature, hereinafter referred to as adeformed state), the display region may become a curved face. As shown,information displayed in the deformation state may be visual informationoutput on the curved face. Such visual information is implemented byindependently controlling light emission of sub-pixels arranged in amatrix. The sub-pixel refers to a minimum unit for implementing onecolor. When external force is applied to the flexible display unit 151,the flexible display unit 151 may be deformed to switch from the defaultstate, which is the flat state, to a bent state, which is not the flatstate.

The flexible display unit 151 may be combined with a touch sensor toimplement a flexible touch screen. When a touch is made on the flexibletouch screen, the controller 180 (see FIG. 1) may perform controlcorresponding to such touch input. The flexible touch screen may beconfigured to detect the touch input in the deformed state as well as inthe basic state.

The touch sensor detects the touch (or touch input) applied on the touchscreen using at least one of various touch schemes such as a resistivefilm scheme, a capacitance scheme, an infrared scheme, an ultrasonicwave scheme, a magnetic field scheme, and the like.

As an example, the touch sensor may be configured to convert a change inpressure applied on a specific portion of the touch screen, capacitancegenerated at the specific portion, or the like into an electrical inputsignal. The touch sensor may be configured such that a touch objectapplying a touch on the touch screen may detect touched position andarea on the touch sensor, a pressure during the touch, a capacitanceduring the touch, and the like.

Further, the mobile terminal 100 may have a deformation detection meansfor detecting the deformation of the flexible display unit 151. Suchdeformation detection means may be included in the sensing unit 140 (seeFIG. 1).

The deformation detection means may be disposed in the flexible displayunit 151 or a case (first to second frames 101 to 102 to be describedlater) to detect information related to the deformation of the flexibledisplay unit 151. In this connection, the information related to thedeformation may include a direction in which the flexible display unit151 is deformed, a degree of the deformation, a deformed position, adeformed time, an acceleration at which the deformed flexible displayunit 151 is restored, and the like. In addition, the information relatedto the deformation may include various kinds of information that may bedetected due to the bending of the flexible display unit 151.

In addition, the controller 180 may change information displayed on theflexible display unit 151 or generate a control signal for controlling afunction of the mobile terminal 100 based on the information related tothe deformation of the flexible display unit 151 detected by thedeformation detection means.

The deformation of the flexible display unit 151 may vary depending onthe positions of the first frame 101 and the second frame 102. As shownin FIG. 2, since the bending position on the flexible display unit 151is determined according to the positions of the first frame and thesecond frame, the bending deformation position of the flexible displayunit 151 and the area thereof positioned on the front may be calculatedbased on the positions of the first frame 101 and the first frame 102 inplace of the deformation detection means of the flexible display unit151.

The state conversion (first or second state) of the flexible displayunit 151, i.e., the size change at the front and rear faces of themobile terminal 100 of the display unit 151 based on the size change ofthe mobile terminal 100 may be performed manually by a force applied bythe user, but may be not limited to such manual scheme. For example,when the mobile terminal 100 or the flexible display unit 151 is in thefirst state, the mobile terminal 100 or the flexible display unit 151may be converted into the second state by the user or an applicationcommand without the external force applied by the user. As such, inorder for the flexible display unit 151 to be automatically deformedwithout the external force, the mobile terminal 100 may include adriving unit 200, which will be described later.

The flexible display unit 151 of the present disclosure is bent 180degrees by rolling around a side portion of the mobile terminal 100facing in the first direction. Accordingly, based on the side portion ofthe mobile terminal 100, a part of the flexible display unit 151 isdisposed on the front of the mobile terminal 100, and the other part ofthe flexible display unit 151 is disposed on the rear of the mobileterminal 100. For simplicity, the part of the flexible display unit 151positioned on the front is called a front face, and the other part ofthe flexible display unit 151 positioned on the rear is called a rearface. As illustrated in FIG. 2, the mobile terminal may extend in thefirst direction or contract in the second direction opposite to thefirst direction. In this case, the area of the flexible display unit 151positioned on the front changes. That is, the sizes of the front faceand the rear face may be changed according to a change in the state ofthe mobile terminal.

The part of the flexible display unit 151 positioned on the front of themobile terminal 100 may be immovably fixed to the front surface of thefirst frame 101, and the other part thereof positioned on the rear ofthe mobile terminal 100 may be movably arranged on the rear of themobile terminal 100.

In addition, the flexible display unit 151 may be rolled on or releasedat the side portion in the first direction of mobile terminal.Accordingly, the rear face of the display unit 151 moves, so that thesize of the front face of the display unit 151 may be adjusted. Sincethe size of the flexible display unit 151 is determined and the flexibledisplay unit 151 is formed of one continuous body, an area of rear faceof the display unit 151 decreases as an area of the front face of thedisplay unit 151 increases. Such a display unit 151 may be rolled in asecond frame 102, which is movable relative to a first frame 101 to bedescribed later, more correctly, on one of sides of the second frame102. The display unit 151 may be withdrawn or pulled out from orinserted or pushed into the second frame 102 while being rolled in thesecond frame 102 along a moving direction of the second frame 102 toadjust the area of the display unit 151 on the front face of the mobileterminal 100. Such operation will be described in more detail belowalong with other relevant components of the mobile terminal 100.

Typically, an antenna is disposed in the case or the housing of themobile terminal 100, but a portion where the antenna is installed in thecase or the housing may be limited because of the flexible display unit151 that covers not only the front face of the mobile terminal 100 butalso the rear face thereof. For this reason, the antenna may beimplemented on the flexible display unit 151. An antenna on display(AOD) is an antenna in which a transparent film is formed by stacking anelectrode layer and a dielectric layer that have patterns engravedthereon, respectively. The antenna on display may be implemented thinnerthan an antenna implemented using a laser direct structuring (LDS)technology using a conventional copper nickel plating scheme, so thatthe antenna on display may not be exposed to the outside withoutaffecting a thickness. In addition, the antenna on display may transmitand receive a signal directly to or from the display unit 151.Accordingly, the antenna on display may be used in the mobile terminal100 in which the display unit 151 is located on the both faces of themobile terminal 100 as in the present disclosure.

FIGS. 4 and 5 are exploded perspective views of the mobile terminal inaccordance with an embodiment. FIG. 4 is an exploded perspective view ofthe mobile terminal as viewed from the front side, and FIG. 5 is anexploded perspective view of the mobile terminal as viewed from the rearside.

The mobile terminal 100 of the present disclosure includes frames 101and 102 in which components are mounted, and the frames 101 and 102 ofthe present disclosure may vary in size in the first direction as shownin FIG. 2. One or more frames 101 and 102 move relative to each other,and sizes thereof may vary in the first direction. Electronic componentsare mounted in the frames 101 and 102, and the flexible display unit 151is located out of the frames 101 and 102.

Since the mobile terminal 100 of the present disclosure includes theflexible display unit 151, the flexible display unit 151 may be combinedin a form surrounding front faces and rear faces of the frames 101 and102. The frame may include the first frame 101 and the second frame 102moving in the first direction with respect to the first frame 101. Thefirst frame 101 and the second frame 102 include front portions, a rearportions, and side portions, respectively, and are coupled to eachother.

First, the first frame 101 corresponds to a main body of the mobileterminal 100, and may have a space between the first front portion 1011and the first rear portion 1012 therein for accommodating variouscomponents. In addition, the first frame 101 may accommodate the secondframe 102 movably coupled to the first frame 101 in such a space. Morespecifically, as shown in FIGS. 2 and 5, the first frame 101 may includea first front portion 1011 disposed at a front portion of the mobileterminal 100 and supporting the front face of the display unit 151 and afirst rear portion 1012 disposed at a rear portion of the mobileterminal and on which various components are mounted. A front deco 1016may cover front edges of the first area 151 a to protect the edges ofthe first area 151 a.

The first front portion 1011 and the first rear portion 1012 may bespaced apart from each other at a predetermined spacing to define apredetermined space therebetween, and may be connected to each other bya first side portion 1013. The first side portion 1013 may be integrallyformed with the first rear portion 1012 or the first front portion 1011.The camera 121, the audio output module 152, and the input/outputterminal, the controller 180, and the power supply unit 190 may beaccommodated as components of the mobile terminal 100 in the space inthe first frame 101. For example, the controller 180 may be a circuitboard 181 including a processor and an electronic circuit forcontrolling the operation of the mobile terminal, and the power supplyunit 190 may be a battery 191 and related components. In addition, thedriving unit 200 that controls the slide movement of the second frame102, which will be described later, may also be accommodated in thefirst frame 101.

As described above, the display unit 151 has the continuous body, andthus, may be disposed on both the front face and the rear face of themobile terminal 100 while being rolled in the mobile terminal 100. Thedisplay unit 151 may include the front face positioned at the front faceof the mobile terminal 100, the rear face positioned at the rear face ofthe mobile terminal 100, and the side face positioned between the frontface and the rear face thereof and surrounding the side face of themobile terminal. The front face and the rear face of the display unit151 are flat, and the side face of the display unit 151 may form acurved face. The flexible display unit 151 may be damaged when beingbent at an angle. Thus, the flexible display unit 151 may be formed tobe bent with a predetermined curvature at the side face.

The display unit 151 may be divided into a fixed portion 151 a and 151 band a variable portion 151 c. The fixed portion 151 a and 151 b means aportion fixed to the frame. Because of being fixed to the frame, thefixed portion 151 a and 151 b maintains a constant shape withoutchanging a bending degree. On the other hand, the variable portion 151 cmeans a portion in which a bending angle or a position of the bentportion changes. The variable portion 151 c in which the position orbending angle of the bent portion changes requires a structure forsupporting a rear face of the variable portion 151 c in response to thechange.

The fixed portion 151 a, 151 b is coupled to the first frame of thedisplay unit and is always positioned on the front face of the displayunit to form a portion of the front face of the display unit. Thevariable portion 151 c includes a side face located at a side portion ofthe mobile terminal, and a position of the side face varies depending onthe position of the second frame. Based on a side face, an area of aportion disposed on the front face of the display unit and an area of aportion disposed on the rear face of the display unit vary. That is, aportion of the variable portion 151 c may be the front face and anotherportion of the variable portion 151 c may be the rear face based on thefirst and second states. The variable portion 151 c is positioned in thefirst direction with respect to the fixed portion 151 a, 151 b relativeto the mobile terminal, and an end of the variable portion 151 c is benttoward the rear face of the mobile terminal and slides on the rear faceof the second frame.

The end of the variable portion of the display unit is coupled with aslide frame that guides the variable portion to slide move on the rearface of the second frame, and the slide frame moves in the firstdirection at the same time as the second frame moves in the firstdirection. As a result, a moving distance of the slide frame withrespect to the first frame is twice as a moving distance of the secondframe with respect to the first frame. Further, as shown in FIG. 3, thefirst rear portion 1012 of the mobile terminal 100 includes an exposedrear portion 1015 that is exposed to the outside without being coveredby the display unit 151 even in the first state. The physical input unit120 for the manipulation of the mobile terminal 100 such as variousbuttons, switches, the camera 121, and a flash, and the sensing unit 140such as the proximity sensor 141 or a fingerprint sensor may be arrangedon the exposed rear portion 1015. The first rear portion 1012 except forthe exposed rear portion 1015 may be covered by the display unit 151 inthe first state as shown in FIG. 3(a), and may be exposed rearward inthe second state as shown in FIG. 3(b).

In a conventional bar-shaped terminal, a display unit is provided onlyon a front face of the terminal. Therefore, a main camera is placed on arear face of the terminal in order for the user to capture an object atan opposite side while looking through the display unit. On the otherhand, an additional auxiliary camera is required to be disposed on thefront face of the terminal in order for the user to capture himself orherself while viewing himself or herself through the display unit.

In the mobile terminal 100 of the present disclosure, on the other hand,the display unit 151 is arranged on both the front and rear of themobile terminal 100. Accordingly, when a user photographs himself, aportion of the display unit 151 positioned on the same surface as thecamera 121, that is, the rear face of the display unit 151 may be used.When the user takes a photograph of an object around the user, a portionof the display unit 151 on the side facing away from the camera 121,that is, the front face of the display unit 151 may be used. For thisreason, the mobile terminal 100 may take a photograph of the user or anobject located around the user using one camera 121. The camera mayinclude a plurality of cameras having different angles of view, such aswide angle, ultra wide angle, and telephoto angle. Not only the camerabut also a proximity sensor and an audio output unit may be disposed onthe exposed rear portion 1015, and an antenna may be installed on therear portion 1015. The rear portion 1015 may be used to protect thecamera, the sensor, or the like on the exposed rear portion 1015 and notto deteriorate the exterior design. A portion of the rear portion 1015corresponding to the camera 121 or the sensor 140 may be configured tobe transparent, and the other portion thereof may have a predeterminedpattern or color in consideration of design aspects without exposinginternal parts.

The first side portion 1013 may extend along the edges of the firstfront portion 1011 and the first rear portion 1012 to surround thecircumference of the first frame 101 and may define the appearance ofthe mobile terminal 100. However, as mentioned above, the second frame102 is accommodated in and movably coupled to the first frame 101, andtherefore a portion of the first frame 101 needs to be open to allowmovement of the second frame 102 relative to the first frame 101. As anexample, as best shown in FIG. 2, the second frame 102 may be movablycoupled to a side of the first frame 101 facing in the first direction,and accordingly the first side portion 1013 may not be formed on thelateral surface facing in the first direction such that the lateralsurface is open. Since the first side portion 1013 is exposed to theoutside of the mobile terminal 100, the interface unit 160 forconnecting a power port or an ear jack or the user input unit 120, suchas a volume control button, may be disposed on the first side portion1013. When the first side portion 1013 contains a metal material, thefirst side portion 1013 may serve as an antenna.

The second frame 102 may include a second front portion 1021 disposed atthe front portion of the mobile terminal 100 and a second rear portion1022 disposed at the rear portion of the mobile terminal 100. Like thefirst front portion 1011 and the first rear portion 1012 of the firstframe 101, the second front portion 1021 and the second rear portion1022 may be formed of plate-shaped members that are generally flat. Inaddition, the second frame 102 also accommodates various components, andmust not interfere with the components accommodated in the first frame101 during the movement. Accordingly, the second front portion 1021 andthe second rear portion 1022 may be coupled to each other in a state ofbeing spaced apart from each other to define a predetermined spacetherebetween, and may have shapes that do not interfere with thecomponents in the first frame 101.

FIG. 6 is a side view of the mobile terminal as viewed from a thirddirection. FIGS. 6(a) and (b) show the first side portion 1013 of thefirst frame 101 and a second side portion 1023 of the second frame 102.Since the flexible display unit 151 is positioned at an end of thesecond frame 102 facing in the first direction, the end of the secondframe 102 facing in the first direction should not be exposed to theoutside. An end of the second frame 102 facing in the second directionshould be open so as not to interfere with the first frame 101. In thefirst state, the second side portion 1023 of the second frame 102, whichis positioned on the side facing in the third direction (which refers tothe upward or downward direction in the drawing or may include both theupward and downward directions), may not be exposed to the outsidebecause it overlaps the first side portion 1013 of the first frame.However, in the second state, it may be exposed to the outside becausethe second frame 102 is drawn out.

In addition, the display unit 151 may be bent 180 degrees while beingrolled in the second frame 102 to be disposed on both the front face andthe rear face of the mobile terminal 100. For such an arrangement of thedisplay unit 151, the second frame 102 may include a roller 210rotatably disposed therein. The roller 210 may be disposed at anyposition inside the second frame 102. However, the display unit 151should be spread flat on the front face and the rear face of the mobileterminal 100 to provide a good quality screen to the user. Further, forsuch spread, a proper tension must be provided on the display unit 151.In order to provide the proper tension, the roller 210 may be disposedat a first directional end of the second frame 102. The roller 210 mayextend in the third direction, and may be rotatably coupled to thesecond frame 102.

The display unit 151 may be rolled around the roller 210 while beinggently bent with a predetermined curvature. The flexible display unit151 may include a first face on which a video is output and exposed tothe outside and an inner face facing the frame at the opposite side. Theroller 210 may be installed to rotate freely in the second frame 102while being in contact with the inner face of the display unit 151.Accordingly, the roller 210 may actually move the display unit 151 in alateral direction of the mobile terminal 100, that is, in a directionperpendicular to a longitudinal direction. As will be described later,when the second frame 102 slides, because of the tension applied by thesecond frame 102, the display unit 151 moves to the front face or therear face of the mobile terminal 100 in different directions (i.e., thefirst direction D1 or the second direction D2) relative to the secondframe 102. The roller 210 may guide such movement while rotating.

The roller 210 may be disposed adjacent to the end of the second frame102 that faces in the first direction. A side frame 1024 may be disposedat the end of the second frame 102 facing in the first direction toprevent damage to the display unit 151 rolled around the roller 210.

The side frame 1024 may extend in the longitudinal direction (the thirddirection) of the second frame 102 to cover the side portion facing inthe first direction, thereby protecting the roller 210 and the displayunit 151 rolled therearound.

The side frame 1024 may substantially define the appearance of themobile terminal 100 in cooperation with the first side portion 1013 ofthe first frame 101. In addition, the side portion of the second frame102 that faces in the second direction may be omitted to minimizeinterference with the components arranged in the first frame 101 duringmovement.

During the expansion and the contraction in such first and seconddirections D1 and D2, the second frame 102 may overlap the first frame101, more precisely, the first front portion 1011 and the first rearportion 1012 thereof so as not to interfere with the first frame 101.More specifically, the display unit 151 may be coupled to and supportedby the first front portion 1011 of the first frame 101, as describedabove. Accordingly, the display unit 151 does not need to beadditionally supported by the second front portion 1021 of the secondframe 102. Rather, when the second front portion 1021 is interposedbetween the first front portion 1011 and the display unit 151, thedisplay unit 151 may be deformed or damaged because of friction with thesecond front portion 1021, which is repeatedly moved. Thus, the secondfront portion 1021 may be disposed below the first front portion 1011,or may be interposed between two first front portions 1011. The secondrear portion 1022 of the second frame 102 may be disposed rearward ofthe first rear portion 1012 of the first frame 101. That is, the frontface of the second rear portion 1022 may face the rear face of the firstrear portion 1012. In addition, the rear face of the first rear portion1012 may be in contact with the front face of the second rear portion1022 to stably support the movement of the second frame 102. Because ofsuch arrangement, the second rear portion 1022 may be exposed to theoutside of the first frame, more precisely, of the first rear portion1012, and may be coupled to the display unit 151.

In addition, the second frame 102 may extend and contract in the firstand second directions D1 and D2 to change the size of the mobileterminal 100, particularly, to extend or contract the front face of themobile terminal 100. Thus, the display unit 151 must move by suchextended or reduced front face size to obtain the intended first andsecond states. However, when being fixed to the second frame 102, thedisplay unit 151 may not be moved smoothly to be adapted for the frontface of the mobile terminal 100 that is extended or contracted. For thisreason, the display unit 151 may be movably coupled to the second frame102.

More specifically, the display unit 151 may include a first region 151 adisposed on the front of the mobile terminal 100, a second region 151 bcoupled to a slide frame 103 positioned on the rear of the mobileterminal 100, and a third region 151 c located between the first region151 a and the second region 151 b and bent around the roller 210. Thethird region 151 c may move to the front or the rear according to changein the state of the mobile terminal 100. The slide frame 103 may beformed of a plate-shaped member extending in the longitudinal direction(the third direction) of the mobile terminal 100, and may be coupled tothe second rear portion 1022 so as to be movable in the first and seconddirections D1 and D2.

The first to third regions 151 a, 151 b, and 151 c may be connected toeach other, and may form a continuous body of the display unit 151. Inaddition, as described above, for the movement of the third region 151 ctoward the front face or the rear face of the mobile terminal 100depending on the moving direction of the second frame 102, the firstregion 151 a may be fixed so as not to move to the front face of themobile terminal 100, and the second region 151 b may be provided to bemovable on the rear face of the mobile terminal. Such configuration ofthe display unit 151 will be described in more detail below.

The first region 151 a may be disposed on the front face of the mobileterminal 100, more specifically, the first frame 101, that is, on thefront face of the first front portion 1011. The first region 151 a isfixed to the first frame 101, that is, the front face of the first frontportion 1011 so as not to be moved during the movement of the secondframe 102, and thus, the first region 151 a may always be exposed to thefront face of the mobile terminal 100.

The third region 151 c may be adjacent to the first region 151 a in adirection facing a second end 151 e. The third region 151 c may extendinto the second frame 102 and be rolled on the roller 210. The thirdregion 151 c may extend out of the second frame 102 and partially coverthe second frame 102, that is, the rear face of the second rear portion1022. Since the second frame 102, i.e., the second rear portion 1022 isadjacent to the first frame 101, i.e., the first rear portion 1012, andthe first and second frames 101 and 102 forms the rear case of themobile terminal 100, it may be said that the third region 151 c is alsodisposed on the rear face of the first frame 101.

The second region 151 b may be adjacent to the third region 151 c andmay be disposed on the rear face of the mobile terminal 100, morespecifically, on the second frame 102, that is, the rear face of thesecond rear portion 1022 thereof. The second region 151 b may be coupledto the slide frame 103 without being directly coupled to the secondframe 102.

As a result, the first region 151 a may be disposed on the front face ofthe mobile terminal 100 and may be always exposed to the front faceregardless of the movement of the second frame 102, and the secondregion 151 b may be disposed on the rear face of the mobile terminal 100and may be always exposed to the rear face regardless of the movement ofthe second frame 102. In addition, the third region 151 c may bedisposed between the first and second regions 151 a and 151 b, and maybe selectively placed on the front face or the rear face of the mobileterminal 100 depending on the moving directions D1 and D2 of the secondframe 102.

Because of such selective placement of the third region 151 c, the firstrear portion 1012 of the first frame 101 may be exposed to the outsideof the mobile terminal 100 because the first rear portion 1012 iscovered by the second and third regions 151 b and 151 c and the secondrear portion 1022 of the display unit 151 in the first state, but, inthe second state, the third region 151 c moves to the front face of themobile terminal 100 and the second rear portion 1022 also moves in thefirst direction D1. In addition, the second front portion 1021 of thesecond frame 102 is hidden by the first front portion 1011 of the firstframe 101 in the first state, but, in the second state, moves out of thefirst frame 101 to support the third region 151 c of the display unit151 disposed on the front face of the mobile terminal 100.

In order to prevent the second front portion 1021 from affecting theinternal components during the slide movement, a separating plate 1017may be further disposed rearward of the second front portion 1021 andfastened with the first front portion 1011. The second front portion1021 may move between the first front portion 1011 and the separatingplate 1017 based on the slide movement of the second frame.

However, the third region 151 c may be rolled on the roller 210 and bentin the second frame 102. When converting from the first state to thesecond state, the third region 151 c may extend from the second frame102 to the front face of the mobile terminal 100 while being rolled onthe roller 210 in one direction. On the other hand, when converting fromthe second state to the first state, the third region 151 c may beretracted from the front face of the mobile terminal 100 to the secondframe 102 while being rolled on the roller 210 in the oppositedirection, and at the same time, may return to the rear face of themobile terminal 100 from the second frame 102.

A specific location of the foldable mobile terminal in a form of beingspread like a book is easily damaged because only the specific locationis folded repeatedly. On the other hand, the deformed portion of theflexible display unit 151, that is, a portion rolled on the roller 210,may vary based on the first and second states of the mobile terminal100, that is, the movement of the second frame 102. Accordingly, themobile terminal 100 of the present disclosure may significantly reducedeformation and fatigue repeatedly applied to a specific portion of thedisplay unit 151, thereby preventing damage to the display unit 151.

Based on the above-described configuration, overall operations of themobile terminal 100 will be described as follows. As an example, thestate conversion may be performed manually by the user, and an operationof the mobile terminal 100 during such manual state conversion will bedescribed. However, operations of the first to third frames 101 to 103and the display unit 151, which will be described below, may beperformed in the same manner when a power source other than a user'sforce is used, for example, when the driving unit 200 to be describedbelow is applied.

A rear face cover 1025 may be further disposed on a rear face of thesecond rear portion 1022 such that the rear face of the display unitpositioned on the rear face of the mobile terminal 100 is not exposed tothe outside. The rear face of the display unit may be used in the firststate when the rear face cover 1025 uses a transparent material, and therear face of the display unit may be covered such that the movement ofthe slide frame 103 is not exposed when the rear face cover 1025 uses anopaque material. That is, the second region and the third region of theslide frame 103 and the display unit 151 may move in the first directionand in the second direction in a space between the second rear portion1022 and the rear face cover 1025.

FIG. 7 is a view showing a driving unit 200 of the mobile terminal 100in accordance with an embodiment. FIG. 7(a) shows the first state andFIG. 7(b) shows the second state. The mobile terminal 100 of the presentdisclosure may be switched between the states in a manner in which auser manually pulls the second frame 102 in the first direction D1 orpushes the same in the second direction D2 with respect to the firstframe 101. However, in the manual method, applying excessive force tothe body of the mobile terminal 100 may damage the mobile terminal 100.Accordingly, a driving unit 200 employing a motor 201 may be furtherprovided to cause the second frame 102 to stably move withoutdistortion.

As the motor 201, a motor 201 configured to provide rotational force asshown in FIG. 7, or a linear motor 201 configured to make linear motionmay be used. The motor 201 configured to provide the rotational forceshould have a large diameter to provide large force. Two motors 201 maybe used as shown in FIG. 7 to provide driving force of a predeterminedmagnitude or more in the limited space of the mobile terminal 100without increasing the thickness.

If the second frame 102 is moved excessively fast, damage or malfunctionmay occur. Accordingly, a planetary gear configured to decrease thespeed of the motor 201 to ensure movement at a stable speed may befurther provided. The planetary gear 202 serves to amplify or attenuatethe number of revolutions of the motor 201 using a plurality of discgears having different numbers of teeth. The motor 201 may be fixed tothe first frame 101 as shown in FIG. 7(a). The position of the motor 201is fixed even when the second frame 102 moves in the first direction toswitch the mobile terminal 100 to the second state, as shown in FIG.7(b).

Since the second frame 102 linearly moves with respect to the firstframe 101 in the first direction or the second direction, rack andpinion gears configured to convert the rotational force of the motor 201into linear motion may be used. A pinion gear to receive the rotationalforce of the motor 201 may be arranged to engage with a rack gear 205composed of teeth continuously arranged in the first direction. Thepinion gear may be fixed to the first frame 101 together with the motor201 and the rack gear 205 may be positioned on the second frame 102.Alternatively, the rack gear 205 may be positioned on the first frame101, and the motor 201 and the pinion gear may be arranged on the secondframe 102. Since the motor 201 holds the pinion gear such that thepinion gear does not rotate, the second frame 102 may maintain the firststate and the second state. However, when large external force isapplied, the second frame 102 may be displaced as the pinion gearrotates.

A stopper (not shown) configured to fix the positions of the secondframe 102 or the rack gear 205 and the first frame 101 may be furtherprovided to fix the mobile terminal 100 in the first state or the secondstate. When electric current flows through the motor 201 to drive themotor 201, the stopper may be released to allow the movement of thesecond frame 102. When power is not applied to the motor 201 and thusthe motor 201 does not rotate, the first frame 101 and the second frame102 may be fastened such that the positions thereof are fixed.

When a pair of driving units 200 is symmetrically disposed in thevertical direction (the third direction), stable movement may be made.However, to arrange a battery or the like, the driving unit 200 shouldbe arranged biased to one side in consideration of the limited mountingspace of the mobile terminal 100 as shown in FIG. 7(a). According tosuch asymmetric arrangement of the driving unit 200, the second frame102 may be distorted during movement due to a difference in movementspeed between the upper end portion and the lower end portion. Toaddress this issue, a linear guide 230 may be further provided.

The linear guide 230 may be disposed at both ends of the mobile terminal100 facing in the third direction, that is, on the upper and lower sidesof the mobile terminal 100, in order to supplement the function of onedriving unit 200 biased to one side in the third direction. The linearguide 230 may include a guide rail 231 extending in the first directionand a guide block 232 configured to move along the guide rail 231. Theguide rail 231 may be disposed on the first frame 101 and the guideblock 232 may be disposed on the second frame 102, or vice versa. Inthis embodiment, the guide rail 231 may be disposed on the second frame102 to cover the upper and lower sides of the extended portion of thesecond frame 102 in the second state.

After the guide block 232 is coupled to the first frame 101 and theguide rail 231 is coupled to the second frame 102, the guide block 232and the guide rail 231 may be slidably fastened to each other. However,for convenience of the fastening, the guide block 232 and the guide rail231 fastened to each other. Then, the guide block 232 may be first fixedto the first frame 101, and then the second frame 102 may be coupled tothe guide rail 231.

The guide block 232 may be provided with a guide groove into which theguide rail 231 is inserted. Alternatively, the guide rail 231 may beprovided with a rail groove into which a portion of the guide block 232is inserted. The fastening portions of the guide rail 231 and the guideblock 232 may be formed to be bumpy. Accordingly, movement in the firstdirection or the second direction may be made without displacement inthe thickness direction of the mobile terminal 100. In order to reducefriction between the guide block 232 and the guide rail 231, aself-lubricating member having high wear resistance and low frictionresistance, such as a bearing or polyoxymethylene (POM), may be added tothe inside of the guide groove.

FIG. 8 is a cross-sectional view taken along lines A-A and B-B in FIG.2. As illustrated in FIG. 2, when the second frame 102 switches to thesecond state by moving in the first direction, the third region 151 cpositioned on the rear side moves to the front, and thus a structure tosupport the rear surface of the third region 151 c moved to the front isrequired. The second front portion 1021 positioned on the front surfaceof the second frame 102 may be positioned on the rear surface of thethird region 151 c in the second state. However, in the first state, thesecond front portion 1021 is disposed to overlap the first front portion1011 of the first frame 101, and accordingly the first front portion1011 and the second front portion 1021 form a step. A boundary is formedbetween the first region 151 a and the third region 151 c of theflexible display unit 151 by the step formed by the first front portion1011 and the second front portion 1021. A rolling hinge 104 may be usedas a support structure to fill the gap between the second front portion1021 and the third region 151 c of the flexible display unit 151.

The rolling hinge 104 may be positioned on the rear surface of theflexible display unit 151, and have a thickness corresponding to the gapbetween the second front portion 1021 and the flexible display unit 151in the second state. As shown in FIG. 8(a), in the first state, therolling hinge 104 is rolled around the roller 210 and is positioned onthe lateral side and rear side of the mobile terminal 100. The flexibledisplay unit 151 and the rolling hinge 104 may be positioned between thesecond rear portion of the second frame 102 and a rear cover 1025provided to cover the rear face of the display unit 151. As shown inFIG. 8(b), when switch to the second state occurs, the rolling hinge 104may move to the front and the rolling hinge 104 may be positioned on thefront portion of the second frame 102.

The third region 151 c of the display unit 151 in which the rollinghinge 104 is positioned is a portion where bending deformation occurswhen switch from the first state to the second state occurs.Accordingly, the rolling hinge 104 may be deformed according todeformation of the third region 151 c. Here, the rolling hinge 104 isrequired to have a predetermined stiffness to maintain the flat statewhen the flexible display unit 151 is positioned on the front or rear ofthe mobile terminal. That is, the rolling hinge 104 needs a structurecapable of maintaining the flat state in the third direction andperforming bending deformation in the first direction.

FIG. 9 is a view illustrating a display unit 151 and a rolling hinge 104of the mobile terminal 100 in accordance with an embodiment. The rollinghinge 104 may include multiple support bars 1041 extending in the thirddirection. The multiple support bars 1041 may be arranged side by sidein the first direction and spaced apart from each other by apredetermined distance. Accordingly, even when the flexible display unit151 is rolled around the roller 210 and is thus bent, interferencebetween the support bars 1041 may be avoided. The support bars 1041 maybe implemented with an injection molding material having a predeterminedthickness for stiffness, and may include materials such as SUS orferrosilicon (FeSi).

The multiple support bars 1041 may be directly attached to the rearsurface of the display unit 151. However, this operation may take a longtime and produce a lot of defects, resulting in poor productivity. Inaddition, directly processing the display unit 151 is highly likely todamage the display unit 151. Therefore, a rolling sheet 1045 to fix themultiple support bars 1041 may be further provided. The rolling sheet1045 may include a metal material, and may employ a superelasticmaterial that is bending-deformable and capable of recovering the flatstate after the bending deformation. For example, a superelastic metalsheet such as a thin STS sheet of 0.05 mm or less may be used. Anadhesive tape may be attached to both surfaces of the rolling sheet 1045to bond the rolling sheet 1045 to the support bars 1041 and bond therear surface of the display unit 151 to the rolling sheet 1045.

The rolling sheet 1045 may be provided with a kerf pattern in whichmultiple grooves extending in the third direction are formed in thefirst direction. The grooves in the kerf pattern may be formed betweenthe multiple support bars 1041. The grooves may be formed on a surfaceof the rolling sheet 1045 to which the support bars 1041 are bonded. Thekerf pattern may be formed in a wedge shape that is formed by beinggradually narrowed from the surface portion of the rolling sheet 1045.

Instead of the rolling sheet 1045, an elastic material such as siliconemay be disposed between the support bars 1041 to join neighboringsupport bars 1041. In this case, the angle between the support bars 1041may be varied. The elastic connector may be bent at a positioncorresponding to the roller 210. When positioned on the front or rear ofthe mobile terminal, the elastic connector may be unfolded such that thesupport bars 1041 are disposed forming a flat surface.

The support bars 1041 may form a flat surface corresponding to the rearsurface of the display unit 151. Alternatively, as shown in FIG. 8(b),the support bars 1041 may be formed in a shape having a predeterminedcurvature. The curved support bars 1041 may closely contact the curvedsurface of the roller 210 when the rolling hinge 104 is rolled aroundthe roller 210. Alternatively, one surface of the support bars 1041 incontact with the display unit 151 maintains a flat state, and the othersurface thereof on the opposite side may include a curved surfacecorresponding to the curvature of the roller 210. In this case, thesupport bars 1041 may be thick at the ends thereof facing in the firstand second directions and have the thinnest portion in the middlethereof.

The rolling hinge 104 may be disposed at a position corresponding to thethird region 151 c and is rolled and bent around the roller 210. Thus,the rolling hinge 104 may span over the front and rear surfaces. Therolling hinge 104 is connected to the first front portion 1011 of thefirst frame 101 on the front side and connected to the slide frame 103on the rear side. In order for the flexible display unit 151 to form acontinuous surface without a step, the first front portion 1011 of thefirst frame 101 positioned on the rear surface of the first region 151a, the slide frame 103 positioned on the rear surface of the secondregion 151 b, and the rolling hinge 104 positioned on the rear surfaceof the third region 151 c may be arranged such that the surfaces thereofin contact with the display unit 151 are at the same height. Inparticular, since the slide frame 103 moves on the rear of the mobileterminal 100 and moves in the same space as the rolling hinge 104, therolling hinge 104 may have a thickness corresponding to the thickness ofthe slide frame 103.

FIG. 10 is a view illustrating an issue raised in an extendable mobileterminal 100. The figure shows the end of the second frame 102 facing inthe third direction when the second frame 102 positioned overlapping thefirst frame 101 is extended as switching from the first state to thesecond state occurs. Since the display unit 151 contains a flexiblematerial, the display unit 151 may be bent at a position correspondingto the roller 210. However, when the display unit 151 is positioned onthe front of the mobile terminal 100 in the second state, it should bemaintained in a flat state. Since the rolling hinge 104 is not fixed tothe second frame 102, the display unit 151 may sag downward as shown inFIG. 10(a) or rise upward as shown in FIG. 10(b).

The sagging issue of the display unit 151 (in FIG. 10(a)) may beaddressed when the support bars 1041 of the rolling hinge 104 describedabove support the rear surface of the third region 151 c of the displayunit 151 and the front portion of the second frame 102 supports thesupport bars 1041. However, in order to address an issue that thedisplay unit 151 moved to the front is not arranged flat but isseparated from the second frame 102 as shown in FIG. 10(b), the rollinghinge 104 and the second frame 102 may further include a slide structure1043, 1027. The slide structures 1043 and 1027 may fasten the rollinghinge 104 (the display unit 151) so as not to be separated from thesecond frame 102 in the thickness direction of the mobile terminal 100while allowing the movement thereof only in the first direction or thesecond direction.

FIGS. 11 to 13 are views showing the slide structures 1043 and 1027provided on the rolling hinge 104 and the second frame 102. FIG. 11 is across-sectional view taken along lines C-C and D-D in FIG. 2, FIG. 12 isa cross-sectional view taken along lines E-E and F-F in FIG. 10, andFIG. 13 is a view showing an expanded side portion 1042 and a guide hook1043 of the mobile terminal 100 in accordance with an embodiment.

As shown in FIG. 13(a), the rolling hinge 104 may include a slide hook1043 protruding toward the second side portion 1023 positioned on theside of the second frame 102 facing in the third direction. As shown inFIG. 11, the second side portion 1023 of the second frame 102 mayinclude a slide rail 1027 into which the slide hook 1043 is movablyinserted. FIG. 11 shows the slide rail 1027 formed on the second sideportion 1023 of the second frame 102. The slide rail 1027 may include apair of horizontal portions 1027 a and 1027 b arranged side by side in athickness direction and a curved portion 1027 c connecting ends of thehorizontal portions 1027 a and 1027 b facing in the first direction. Thepair of horizontal portions 1027 a and 1027 b and the curved portion1027 c may form a U shape, and the slide hook 1043 may move along theslide rail 1027.

In the first state, the slide hook 1043 may be positioned in thehorizontal portion 1027 a, 1027 b positioned on the rear side, as shownin FIG. 11(a). In the second state, the slide hook 1043 may be moved tothe horizontal portion 1027 a, 1027 b positioned on the front side, asshown in FIG. 11(b). When moved from the rear horizontal portion 1027 a,1027 b to the front horizontal portion 1027 a, 1027 b, the slide hook1043 may pass through the curved portion 1027 c. When the slide hooks1043 pass through the curved portion 1027 c, the rolling hinge 104 maybe bent and the space between the slide hooks 1043 may be narrowed.

The slide rail 1041 along which the slide hook 1043 moves may guide themovement of the slide hook 1043 and the movement of the slide frame 103simultaneously. Since the slide frame 103 is also disposed adjacent tothe support bars, a slide hook 1033 protruding from the slide frame 103may be further provided.

FIG. 12(a) shows the second frame 102 in the first state in which thefirst frame 101 and the second frame 102 overlap each other, and FIG.12(b) shows the second frame 102 moved from the first frame 101 in thefirst direction in the second state. As shown in FIG. 12(a), the supportbars 1041 and the slide hooks 1043 are positioned on the rear in thefirst state. In the second state, as shown in FIG. 12(b), the supportbars 1041 and the slide hooks 1043 are positioned on the front. Thedistance from the front face of the display unit 151 to the fronthorizontal portions 1027 a and 1027 b may be equal to the distance fromthe rear face of the display unit 151 to the rear horizontal portions1027 a and 1027 b.

When large friction occurs during movement of the slide hooks 1043 alongthe slide rail 1027, a large load may be applied to the driving unit200, thereby generating frictional noise or affecting the durability ofthe product. A self-lubricating member having high abrasion resistanceand low friction resistance, such as polyoxymethylene (POM), may be usedto facilitate the movement of the slide hooks 1043 on the slide rail1027. By forming the slide hooks 1043 in a cylindrical shape, the areathereof in contact with the slide rail 1027 may be minimized.

As illustrated in FIG. 13(b), a slide roller 1044 fitted onto the slidehook 1043 may be further provided. The slide roller 1044 may be fittedonto the cylindrical slide hook 1043 to rotate about an axis extendingin a direction in which the slide hook 1043 protrudes. The slide roller1044 may rotate when the slide hook 1043 moves along the slide rail1027, thereby reducing friction generated between the slide roller 1044and the slide rail 1027.

A bearing structure may help to reduce the friction, but it may increasethe overall size. For this reason, a simple ring-shaped slide roller1044 may be used. A fastening groove 1043 a and a fastening protrusion1044 a may be further provided to prevent the slide roller 1044 frombeing separated from the slide hook 1043. When the fastening protrusion1044 a is inserted into the fastening groove 1043 a, the fasteninggroove 1043 a formed on the outer circumferential surface of the slidehook 1043 in a ring shape and the ring-shaped fastening protrusion 1044a protruding from the inner surface of the slide roller 1044 arefastened to each other.

The second side portion 1023 of the second frame 102 is disposedoverlapping the first side portion 1013 of the first frame 101 in thefirst state, and is exposed to the outside in the second state. Sincethe second side portion 1023 is positioned inside the first side portion1013 of the first frame 101 in the first state, it may be difficult toconnect the interface unit 160, the user input unit 123, the audiooutput unit 152, the antenna, and the like, which are positioned on thefirst side portion 1013, to the printed circuit board 181, which ispositioned inside.

The second side portion 1023 may include an opening 1023 a formed byomitting at least a part of the second side portion 1023 to connect thecomponents positioned on the first side portion 1013 to the printedcircuit board 181 positioned inside the first frame 101. Through theopening 1023 a, a connector may be arranged between the componentspositioned on the first side portion 1013 and the printed circuit board.The opening 1023 a may have a shape elongated in the first direction toprevent interference between the connector and the second side portion1023 of the second frame 102 even when the second frame 102 is moved.

However, in order to prevent the inside of the mobile terminal 100 frombeing exposed through the opening 1023 a in the second state, anexpanded side portion 1042 may be formed at an end of the support bar1041 to cover the opening 1023 a in the second state. The expanded sideportion 1042 may have a larger area than the cross section of thesupport bar 1041 at the end of the support bar 1041. The slide hook 1043may be formed on a first expanded side portion 1042 a extending in adirection away from the display unit 151. When the slide hook 1043 isdisposed parallel to the support bar 1041, the second side portion 1023of the second frame 102 should be extended adjacent to the display unit151, which may make it difficult to form the opening 1023 a.Accordingly, the slide hooks 1043 may be formed at positions spacedapart from the display unit 151 by a predetermined distance. The firstexpanded side portion 1042 a may be formed in a fan shape to have awidth that is reduced as the first expanded side portion 1042 a extendsin a direction away from the display unit 151. FIG. 13 is a view showingan embodiment of the rolling hinge 104 of the mobile terminal 100. Sincethe rolling plates at positions on the curved portion 1027 c of theslide rail 1027 spaced apart from the display portion 151 are disposedadjacent to each other, the first expanded side portion 1042 a may beformed in a fan shape to prevent the rolling plates from overlappingeach other.

The expanded side portion 1042 may also extend in the left-rightdirection, and may thus cover a space between neighboring support bars1041. The expanded side portion 1042 may further include a secondexpanded side portion 1042 b forming a step with respect to the firstexpanded side portion 1042 a as shown in FIG. 13. The second extensionside portion 1042 b may be disposed to overlap the first expanded sideportion 1042 a adjacent thereto to cover the space between the supportbars 1041. The second expanded side portion 1042 b may have a sizecorresponding to the thickness-wise size of the opening 1023 a formed inthe second side portion 1023 of the second frame 102. The secondexpanded side portion 1042 b may be formed to be shorter than the firstexpanded side portion 1042 a on the side spaced apart from the displayunit 151.

The second expanded side portion 1042 b may be formed to be shorter thanthe first expanded side portion 1042 a to prevent the second expandedside portions 1042 b from overlapping each other when the rolling platespass through the curved portion 1027 c of the slide rail 1027. Thesecond expanded side portion 1042 b may be formed to have a sizecorresponding to the size of the opening 1023 a to cover the spacebetween the first expanded side portions 1042 a to prevent the inside ofthe second frame 102 from being exposed to the outside.

FIG. 14 is a view showing the slide frame 103 and the second frame 102of the mobile terminal 100. Like the rolling hinge 104, the slide frame103 is positioned on the rear surface of the display unit 151 and movestogether with the display unit 151. The rolling hinge 104 moves to theback and front of the mobile terminal 100, but the slide frame 103 movesonly on the back of the mobile terminal 100, that is, on the second rearportion 1022 of the second frame 102. A structure to guide the slideframe 103 to linearly move in the first direction or the seconddirection without distortion is needed. A guide slot extending in thefirst direction may be formed in the rear surface of the second frame102 and the slide frame 103 may be configured to move along the guideslot.

However, since the second side portion 1023 of the second frame 102includes the slide rail 1027 extending in the first direction asdescribed above, the movement of the slide frame 103 may be guidedthrough the slide rail 1027, into which the slide hook 1043 of therolling hinge 104 is inserted, without forming a separate guide rail. Asshown in FIG. 15, slide hooks 1033 may be formed at both ends of theslide frame 103 to guide the slide frame 103 to move along the sliderail 1027. The slide hooks 1033 of the slide frame 103 may have a shapesimilar to that of the slide hook 1043 of the rolling hinge 104. Theslide hooks 1033 protrude from the display unit 151 in a direction awayfrom the display unit 151. However, since the slide hooks 1033 of theslide frame 103 do not move to the front, they move only on a firsthorizontal portion.

Since the slide frame 103 and the rolling hinge 104 move along the sliderail 1027, movement in the first direction and movement in the seconddirection may be guided stably, and the issue of separation of thedisplay unit 151 from the second frame 102 may be addressed. However,since the slide rail 1027 is positioned at the end facing in the thirddirection, the middle portion of the slide frame 103 in the thirddirection may be separated from the second frame 102. To prevent theseparation at the middle portion of the slide frame 103 while both endsof the slide frame 103 are fixed to the frame 102, a magnetic materialmay be used.

FIG. 15 is a graph showing phase distortion in the mobile terminal 100,and FIG. 16 is a conceptual view for explaining causes of the phasedistortion of FIG. 15.

The flexible display unit 151 may include a portion (fixed portion)attached to the first frame 101 and a portion (variable portion) notattached to the first frame 101 or a bending portion. The first region151 a is fixed to the first frame 101, but the second region 151 b isnot fixed to the first frame 101 so that it is capable of bending ormoving to the front and rear side.

In FIG. 15, {circle around (1)}, {circle around (2)}, and {circle around(3)} respectively show phase distortion in the display unit 151 at thetop, middle, and bottom of the fixed portion, and {circle around (4)},{circle around (5)}, and {circle around (6)} respectively show phasedistortion in the display unit 151 at the top, center, and bottom of thevariable portion. Since the fixed portion is fixed to the first frame101, the amount of phase distortion is relatively low. In particular,since the center part is more stably attached to the first frame 101than the top and bottom parts, the amount of phase distortion at thecenter part is lower than the top and bottom parts.

However, since an end in the second direction, i.e., the left end in thedrawing is attached to the first frame 101 while being bent as shown inFIG. 16, it may have a repulsive force to the flatness of the displayunit 151. As a result, phase distortion may occur at the end in thesecond direction. In addition, the end of the fixed portion facing inthe first direction is adjacent to the variable portion, phasedistortion may occur thereat due to the deformation of the variableportion.

The rear surface of the variable portion is supported by the rollinghinge 104. However, since the rolling hinge 104 has a deformablestructure unlike the frames, the phase distortion at the fixed portionmay increase. The phase distortion may increase at a point between thefixed and variable portions where the support structure (e.g., frame orrolling hinge) is partially omitted on the rear surface thereof.Further, the phase distortion may also increase at a point where thevariable portion is rolled on the roller 210.

Referring to FIG. 16, the phase distortion at the end of the fixedportion facing in the second direction, the point between the fixed andvariable portions, and the point where the variable portion is rolled onthe roller 210 may be convex outward, whereas the phase distortion atthe center of the fixed portion attached to the first frame 101 may bereverse to the former distortion.

The phase distortion at the center of the variable portion is similar tothat of the fixed portion. A line distinguishing between the support bar1041 and a portion combined with the support bar 1041 of the rollinghinge 104 on the rear surface may appear on the display unit 151.

To minimize the phase distortion, the display unit 151 needs to be in atight state. To reduce vertical distortion in the display unit 151, thevariable portion of the display unit 151 should be flat.

Since the end of the third region (variable portion) facing in thevertical direction (third direction) is fixed by the liner guide 230,there may be no waviness. However, since there may be waviness in thecenter thereof facing in the third direction, a rail 1029, a rivet 1047,or slide rivets 1039 and 1049 may be used to prevent the second area 151b or the third area 151 c from being separated from the second frame102.

One reason why the display unit 151 has waviness as shown in FIG. 16 isthat the display unit 151 consists of a plurality of layers and a slipphenomenon occurs for each layer due to the radius of curvature. Inparticular, the phase distortion may occur in the third region 151 c ofthe flexible display unit 151 since the waviness is easily formed in thethird region 151 c.

The third region 151 c of the flexible display unit 151 is the variableportion capable of moving from the front surface to the rear surface andvice versa. The variable portion 151 c bends and surrounds the end ofthe second frame 102 facing in the first direction, and the bendingposition varies depending on the position of the second frame 102.

The rolling hinge 104 for supporting the variable portion 151 c isdisposed on the rear surface of the variable portion 151 c, and therolling hinge 104 may be deformable. That is, since the variable portion151 c has a laminate structure in which multiple components are layered,the distortion may further increase therein.

FIG. 17 is a view for explaining a slip phenomenon occurring whencurvature changes in a structure consisting of a plurality of layers (L1and L2). FIG. 17 (a) shows a state in which the plurality of layers (L1and L2) are flat, and FIG. 17 (b) shows a state in which the pluralityof layers (L1 and L2) are bent. The layer may be made of high elasticmetal such as SUS, titanium, etc.

When a pair of layers (L1 and L2) with the same length (L) are flat asshown in FIG. 17 (a), if the layers are bent as shown in FIG. 17 (b),the ends of the layers may be dislocated by g due to a differencebetween the radius of curvature (R) of the layer (L1) located outsidewith respect to the bending deformation position and the radius ofcurvature (r) of the layer (L2) located inside with respect to thebending deformation position (R>r).

The tolerance g depends on the difference between the radius ofcurvature (R) of the outside layer (L1) and the radius of curvature (r)of the inside layer (L2), and it is obtained by multiplying thecurvature radius difference (R−r) by n/2. A difference betweendeformation lengths is obtained by multiplying the curvature radiusdifference (R−r) by π. Since the difference is distributed over theends, it decreases by a half. Since the curvature radius difference(R−r) is equivalent to the sum of the thickness of the outer layer andthe distance between the two layers (L1 and L2), it may be representedby g=n/2*(t+c).

The two layers (L1 and L2) may be dislocated by the tolerance g, whichdepends on the curvature radius difference between the two layers (L1and L2), and the slip phenomenon may depend on a distance from thecurved area of the variable portion.

FIG. 18 is a view for explaining an embodiment of coupling the pluralityof layers (L1 and L2) with an adhesive (A). The plurality of layers (L1and L2) need to be coupled such that they are not spaced apart from eachother in the thickness direction and are capable of accepting tolerance,which depends on bending deformation. In particular, when the locationof the curved area of the variable portion changes as described in thepresent disclosure, the plurality of layers need to be coupled to eachother such that the position tolerance between the layers are easilyaccepted.

As shown in FIG. 18(a), the elastic adhesive (A) may be applied betweenthe two layers (L1 and L2). The adhesive (A) may be an optically clearadhesive (OCA) or a high elastic adhesive. In addition, the adhesive (A)may be deformable and accept the tolerance g between the layers (L1 andL2). However, since the adhesive (A) tends to be restored to theoriginal shape due to elasticity, there may be a repulsive force whenthe display unit 151 is bent.

When the support bar 1041 of the rolling hinge 104 is attached as shownin FIG. 18(b), the cohesive strength may increase at a location wherethe support bar 1041 is disposed due to the elasticity of the adhesive(A), but it may decrease at a location where the support bar 1041 is notdisposed. Thus, waviness occurs on the front surface of the display unit151 depending on the position of the support bar 1041. That is, there isa problem that the support bar 1041 is transferred.

FIG. 19 is a view showing an embodiment of the plurality of layers ofthe mobile terminal 100, and FIG. 20 is a cross-sectional view takenalong line G-G of FIG. 19. The plurality of layers may include all platemembers disposed between the support bar 1041 of the rolling hinge 104and the display unit 151. In some embodiments, the plurality of layersmay include a display plate disposed on the rear surface of the displayunit 151. For convenience of description, all plate members disposedbetween the display unit 151 for displaying and the support bar 1041 areassumed to be the rolling sheet 1045.

When the layers are coupled to each other using the above-describedadhesive (A), it may have the following problems: the repulsive force isgenerated due to the elasticity of the adhesive (A) and the support bar1041 is transferred. Accordingly, it is proposed in this embodiment tocouple each rolling sheet 1045 with the rivet 1047. Although FIG. 20shows an embodiment in which two rolling sheets 1045 are coupled, threerolling sheets may be coupled as shown in FIG. 21. Further, three ormore rolling sheets 1045 may be coupled.

Each rolling sheet 1045 includes a plurality of hinge holes 1048. Thehinge hole 1048 is elongated in the third direction, and the pluralityof hinge holes 1048 may be arranged and spaced apart from each other inthe first and third directions. The hinge holes 1048 spaced from eachother in the first direction may be arranged in a zigzag manner. A linejoining the end of each hinge hole 1048 facing in the third directionmay be a zigzag line, instead of a straight line in the first direction.When the plurality of hinge holes 1048 are arranged as described above,the plurality of hinge holes 1048 may allow the rolling sheet 1045 tohave a variable length in the first direction. The hinge holes 1048spaced apart from each other in the first direction may be partiallycontinuous in the third direction with no gaps, and thus there is nolength change in the third direction.

Each of the plurality of rolling sheets 1045 is elongated in the thirddirection and includes the plurality of hinge holes 1048 arranged in thefirst and third directions. The hinge holes 1048 may not necessarilyoverlap with each other, but the hinge holes 1048 may overlap at leastpartially so that the rivet 1045 penetrates the hinge holes 1048.

FIG. 20 is a cross-sectional view taken along line G-G of FIG. 19. Inparticular, FIG. 20 shows the embodiment in which two rolling sheets1045 are included. In FIG. 20, a first rolling sheet 10451 overlaps witha second rolling sheet 10452. Specifically, FIG. 20 shows the crosssection of an area in which a first hinge hole 10481 formed in the firstrolling sheet 10451 overlaps with a second hinge hole 10482 formed inthe second rolling sheet 10452.

In FIG. 20, the left direction corresponds to the first direction. FIG.20(a) shows a state in which the rolling sheet 1045 is flat as shown inFIG. 19, and FIG. 20(b) shows a state in which the rolling sheet 1045shown in FIG. 19(a) is bent. A first rivet 10471 penetrating the firstand second hinge holes 10481 and 10482 has a width (w1) in the firstdirection smaller than the width (w2) of the first and second hingeholes 10481 and 10482. Although it is illustrated that the first andsecond hinge holes 10481 and 10482 have the same size, the first andsecond hinge holes 10481 and 10482 may have different sizes if the sizeof the first rivet 10471 changes.

The first rivet 10471 may move within the first and second hinge holes10481 and 10482. However, to prevent the first rivet 10471 from beingseparated from the first and second hinge holes 10481 and 10482, thefirst rivet 10471 may have wings at both ends, each of which has a width(w3) greater than the width (w2) of the first and second hinge holes10481 and 10482 (w3>w2). The wing may be formed by inserting an extramember into the rivet 1047 after the rivet 1047 is fastened.Alternatively, the wing 1047 b may be formed by pressing and extendingthe end of the rivet 1047.

When the rolling sheet 1045 is bent as shown in FIG. 20(b), the positionof the first rivet 10471 within the first and second hinge holes 10481and 10482 may change in response to a position change caused by slidingof the rolling sheet 1045 since there is a space between the first rivet10471 and the first and second hinge holes 10481 and 10482. The firstrivet 10471 may not necessarily inserted into all the hinge holes 1048,but the first rivet 10471 may be inserted into several hinge holes 1048.

FIG. 21 is an exploded perspective view of FIG. 19, and FIG. 22 is across-sectional view taken along line G-G of FIG. 19. In particular,FIG. 22 shows an embodiment in which three rolling sheets 1045 areincluded. In addition to the two rolling sheets 1045 of FIG. 20, a thirdrolling sheet 10453 overlapping with the second rolling sheet 10452, maybe further included.

The second rolling sheet 10452 may further include a third hinge hole10483, and the third rolling sheet 10453 may include a fourth hinge hole10484, which overlaps at least partially with the third hinge hole10483. Similarly to the first and second hinge holes 10481 and 10482,the third and fourth hinge holes 10483 and 10484 may be elongated in thethird direction, and a plurality of third and fourth hinge holes 10483and 10484 may be arranged in the first and third directions.

The second and third hinge holes 10482 and 10483 may be arrangedalternately in the first direction. The first rivet 10471 may penetratethe second hinge hole 10482 for coupling with the first rolling sheet10451, and the second rivet 10472 may penetrate the third hinge hole10483 for coupling with the third rolling sheet 10453. To couple thethree rolling sheets 1045 stably, the second and third hinge holes 10482and 10483 may be formed alternately in the first direction.

FIG. 22(a) shows a state in which the rolling sheet 1045 is flat asshown in FIG. 19, and FIG. 22(b) shows a state in which the rollingsheet 1045 shown in FIG. 22(a) is bent. Similarly to the embodiment ofFIG. 20, the second rivet 10472 may have a width (w4) in the firstdirection smaller than the width (w5) of the third and fourth hingeholes 10483 and 10484. In addition, the second rivet 10472 may have awing wider than the width of the first and second hinge holes 10481 and10482 (w6>w5).

When the three rolling sheets 1045 are coupled, spaces formed betweenthe first to fourth hinge holes 10481 to 10484 and the first and secondrivets 10471 and 10472 may accept tolerance that depends on the bendingdeformation of the first and third rolling sheets 10451 to 10453, aswhen the two rolling sheets 1045 are included.

Instead of using an adhesive, the rivet 1047 penetrating the hinge hole1048 is used for coupling between the plurality of rolling sheets 1045,thereby preventing stress from increasing due to the repulsive force ofthe adhesive.

The compression of the adhesive, which occurs at the coupling point ofthe support bar 1041, may be resolved, thereby providing a screen withno waviness and preventing the support bar 1041 from being transferredto the variable portion.

The above-described embodiments are to be construed in all aspects asillustrative and not restrictive. The scope of the disclosure should bedetermined by the appended claims and their legal equivalents, not bythe above description, and all changes coming within the meaning andequivalency range of the appended claims are intended to be embracedtherein.

What is claimed is:
 1. A mobile terminal comprising: a body comprising:a first frame; and a second frame configured to slide in a firstdirection with respect to the first frame and to slide in a seconddirection opposite to the first direction with respect to the firstframe; a flexible display configured to cover a part of the body,wherein a front surface area of the flexible display varies according tothe sliding of the second frame; and a rolling hinge disposed at a rearsurface of the flexible display and deformable in response to a bendingdeformation of the flexible display, wherein the rolling hingecomprises: a first rolling sheet comprising a plurality of first hingeholes, a second rolling sheet disposed at a rear side of the firstrolling sheet in a thickness direction of the mobile terminal, whereinthe second rolling sheet comprises a plurality of second hinge holes,and a plurality of first rivets, wherein each first rivet is configuredto pass through one of the plurality of first hinge holes and one of theplurality of second hinge holes to at least partially overlap eachother, wherein ends of the plurality of first hinge holes with respectto a third direction perpendicular to the first direction are arrangedadjacent to each other in an offset manner in the first direction andwherein ends of the plurality of second hinge holes with respect to thethird direction are arranged adjacent to each other in an offset mannerin the first direction.
 2. The mobile terminal of claim 1, wherein thefirst rivet is smaller than the plurality of the first and second hingeholes in the first direction.
 3. The mobile terminal of claim 2, whereinthe first rivet comprises a first wing at a first end of the first rivetand a second wing at a second end of the first rivet, wherein the firstwing and the second wing are each greater than the plurality of thefirst and second hinge holes in the first direction.
 4. The mobileterminal of claim 1, wherein the plurality of first hinge holes arrangedand spaced apart from each other in the first direction and in the thirddirection, and the plurality of second hinge holes arranged and spacedapart from each other in the first direction and in the third direction.5. The mobile terminal of claim 1, wherein the plurality of first hingeholes and the plurality of second hinge holes are elongated in the thirddirection.
 6. The mobile terminal of claim 1, wherein the second rollingsheet further comprises a third hinge hole, and wherein the rollinghinge further comprises: a third rolling sheet overlapping with thesecond rolling sheet, wherein the third rolling sheet comprises a fourthhinge hole at least partially overlapping with the third hinge hole; anda second rivet configured to pass through the third hinge hole and thefourth hinge hole.
 7. The mobile terminal of claim 6, wherein the thirdhinge hole is one of a plurality of third hinge holes arranged andspaced apart from each other in the first direction and in a thirddirection perpendicular to the first direction, and the fourth hingehole is one of a plurality of fourth hinge holes arranged and spacedapart from each other in the first direction and in the third direction.8. The mobile terminal of claim 1, wherein the rolling hinge comprises aplurality of support bars coupled to the first rolling sheet andarranged side by side along the first direction, wherein each of theplurality of support bars extends in a third direction perpendicular tothe first direction.
 9. The mobile terminal of claim 1, wherein theflexible display comprises: a fixed portion coupled to the body; and avariable portion capable of bending deformation, wherein the variableportion is not coupled to the body, and wherein the rolling hinge isdisposed at a rear surface of the variable portion.